The present invention relates to improvements in plastic sliders for opening and closing plastic reclosable fasteners on plastic bags and the like and the method of assembling a foldable plastic slider with a profiled plastic reclosable fastener on the plastic bags.
Zippers with sliders are made commercially in several forms. The most common ones used on clothing have teeth which interlock. The teeth may be made of metal or plastic. Other types of plastic zippers have profiles and include a pair of male and female fastener elements in the form of reclosable interlocking rib and groove elements with a slider for opening and closing the rib and groove elements. In the manufacture of thermoplastic film bags, a pair of these male and female fastener elements extend along the mouth of the bag and these male and female elements are adapted to be secured in any suitable manner to the flexible walls of the thermoplastic film bag. These elements may be integral marginal portions of such walls or they may be extruded separately and thereafter attached to the walls along the mouth of the bag. A method of continuously providing such a fastener on the thermoplastic film is disclosed in U.S. Pat. No. 3,462,332.
The sliders for opening or closing the reclosable fasteners are essentially U-shaped and adapted to be assembled with the fastener or zipper by an endwise assembly or by a relative transverse maneuver. Where the assembly is performed by a relative transverse maneuver the slider is normally molded from a semi-hard plastic where there is enough yieldability in the side walls of the slider to provide sufficient flexibility to enable spreading apart of the terminal portions of the side walls of the slider so as to clear the interlocking rib and groove elements to permit assembly of the slider with the zipper by relative transverse movement. Where the slider is formed from a metal die casting or a hard plastic, it is then necessary to rely upon the plastic deformation of the plastic zipper elements to permit the transverse assembly movement of the slider. Such assembly can cause damage to the interlocking rib and groove elements during assembly and leaves something to be desired. Examples of assembly of the sliders with plastic reclosable fasteners are disclosed in U.S. Pat. Nos. 3,426,396, 3,660,875, 3,713,923, 3,790,992 and 3,806,998.